Exclude file paths always use forward slash but tests currently change
based on which OS is running them, so this bug never got caught.
Bug: 1440473
Change-Id: Iafd7e57c2dedd0c9990a1a620abd3ae38631a4f6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/4481518
Reviewed-by: Sean McCullough <seanmccullough@google.com>
Commit-Queue: Gavin Mak <gavinmak@google.com>